1. Field Of The Invention:
The present invention relates to sugar cane harvesters and more particularly relates to an improved wholestalk sugar cane harvesters of the type wherein a base cutter severs the cane at or near ground level and a topper severs the upper portion of the cane to remove leafy material with the cane wholestalks being conveyed through the harvester and discharged to the rear or to left or right sides of the machine for subsequent loading into cane carts. More particularly, the present invention relates to an improved two row wholestalk type sugar cane harvester wherein two rows of cane are harvested simultaneously and wherein an improved base cutter position control device automatically raises or lowers the base cutter to compensate for changes in the elevation of the underlying terrain so that the cane is always cut very close to ground level eliminating the substantial waste of the base cutter cutting the cane too high above ground level.
Even more particularly, the present invention relates to an improved sugar cane harvester having a base cutter position control device that selectively adjusts the position of the base cutter depending upon changes in ground level elevation and changes in wheel positions, as when one or more of the harvester wheels sinks into the mud.
2. General Background:
In the harvesting of sugar cane, there is typically employed a harvester which can be a "billet" type harvester (also known as a chopper harvester) or a wholestalk harvester. A billet type or chopper harvester chops the cane off at its base, near ground level and then chops that stalk into small sections of for example six inches to twelve inches (6"-12") in length. A wholestalk harvester leaves the cane in substantially a single wholestalk form because the cane is only cut in two positions, namely at the top and at the bottom. With a wholestalk harvester, a base cutter chops the cane at or near ground level while a topper cuts the upper most portion of the cane to eliminate the leafy material that is predominantly found on the top end portion of the stalk. Wholestalk harvesters then convey the cut cane through the machine and pile the cane behind the machine or to the sides of the machine in parallel fashion. An example of a two row wholestalk harvester can be seen in the Richard Duncan U.S. Pat. No. 4,380,281, which is incorporated herein by reference. Several Massey Ferguson owned patents have been issued which relate to billet or chopper harvesters. An example is U.S. Pat. No. 3,848,399 issued to Sam R. Makeham and assigned to Massey Ferguson, Ltd.
During use, a wholestalk harvester can encounter changes in the elevation of the underlying terrain, undulating terrain, and soft or low spots in the terrain such as ruts, potholes, soft spots, uneven cultivation etc. These changes in terrain cause the harvester to tip from one side to the other, or in a fore/aft direction or to sink with respect to a pure horizontal plane so that the base cutter moves upwardly and downwardly constantly changing the position of the cut with respect to the ground surface.
If the wheels of the harvester sink into the mud, the harvester can actually cut the stalk too low, and even below the ground surface. If the wheels of the harvester engage a high spot, the base cutter rises a few inches above its normal operating position, cutting high on the cane stalk and wasting that portion of the cane stalk between the ground surface and the position of the cut (which can be a substantial waste of several inches of cane stalk. This waste factor can be extensive, considering an entire crop of thousands of acres of cane for example.
Therefore, there is a need for a wholestalk sugar cane harvester having an improved base cutter arrangement that automatically controls the position of the base cutter with respect to the cane being cut, notwithstanding changes in position of the harvester wheels and notwithstanding the change in elevation of the terrain which the harvester can encounter on a continual basis. It is thus necessary to constantly monitor and adjust the base cutter position. Several devices have been patented that relate to sugar cane harvesters and to sugar harvesters systems, some of which relate to base cutters and some of which relate to mechanisms for raising and lowering base cutters.
In the Douglas U.S. Pat. No. 2,953,886 entitled "Sugar Cane Harvester With Cutting Apparatus" there is shown an early version of a sugar cane harvester having a tractor with a side mounted harvester portion that includes a pair of base cutter blades.
In the Mizzi U.S. Pat. No. 3,307,338, a sugar cane harvester is of a side mounted variety that is equipped with a base cutter. The harvester cuts cane stalks into pieces which are thrown rearwardly by a rotary chopping cutter.
In the Sexton U.S. Pat. 3,456,429 there is provided a sugar cane harvesting apparatus having a forward portion that carries a base cutter. The forwardly extending portion is supported upon wheels that are much smaller than the wheels which support the majority of the harvester.
In the above mentioned Makeham U.S. Pat. No. 3,848,399 entitled "Sugar Cane Harvesters" there is provided a harvester having twin contra-rotating base cutters feeding whole sticks to each cane chopping apparatus which subdivides the sticks. Each base cutter is in the form of a drum, open at one end and arranged with its open end facing downwards. Outwardly projecting blades are mounted at the open end of the drum. The blades are thereby downwardly offset from the closed end of the drum which reduces power consumption and causes less soil and stones to be fed into the harvester with cane sticks.
Base cutters are shown in the Quick U.S. Pat. No. 4,019,308 entitled "Base Cutting Apparatus for Sugar Cane Harvesters". The '308 Quick patent provides a sugar cane harvester having a pair of contra-rotatable base cutters with projecting blades to sever cane sticks from their roots. The base cutters are constructed to minimize the quantity of earth fed into the harvester with the crop. A large free area is provided between the successive blades for earth and rocks to drop out, but each blade has a long exposed cutting edge to prevent cane sticks entering the area without being cut. The blades are mounted on a support member having a flat profile to minimize the paddling action of the base cutters on earth and rocks.
A harvester combine is the subject of the Fernandez U.S. Pat. No. 4,035,996 in which a frame is pivotally mounted on a chassis of a self-propelled vehicle so as to be at least partially suspended beyond the front of the chassis. A plurality of cutter mechanisms, one of which is movable with respect to the ground, are provided for cutting the crop to be harvested. A conveyor transports the cut, harvested crop and extraneous material rearwardly to a cleaning chamber in which the cut harvested crop is separated from the extraneous material and is separately recovered.
A machine for harvesting sugar cane is the subject of U.S. Pat. No. 4,070,809 entitled "Automatic Sugar Cane Harvesting Machine". The harvester runs on a pair of driving wheels and a pair of guide wheels. At the front of the machine there is arranged a pair of arms, the ends of which rest on the ground and on which are mounted a pair of rotating conical members which lift the sugar cane which is to be cut near its base by a pair of rotating cutters, the height of which is controlled by the pair of arms. The cut stems are then sliced into pieces by blades mounted on a rotating drum which blades cooperate with bars mounted on a second rotating drum. The cut pieces of cane, together with the waste lighter elements are then projected towards an elevator through an airflow from a nozzle which carries away the waste and allows the cane to reach the elevator.
In the Moreno et al. U.S. Pat. No. 4,170,098, an apparatus for harvesting sugar cane employs a self-propelled chassis for the harvesting of sugar cane employing copying wheels for following the microrelief of the ground responsive to movement in a harvesting section of the apparatus. A cross-cutting assembly employing two differently dimensioned drums with offset blades is used to cut the cane, and an associated pneumatically operated cleaning chamber employs dispersing drums, veins and shutters in conjunction with specifically placed blowers, which act upon foreign matter during the harvesting operation and eject the same to the outside chamber where it is deflected to a desired location.
The Landry U.S. Pat. No. 4,512,142 entitled "Scroll Type Gatherer and Top Shredder With Longitudinal Blades for Sugar Cane Harvesters" shows an attachment for a sugar cane harvester for gathering, severing or chopping or shredding the nonmillable immature top portions of a sugar cane stalk so that the remaining millable portion of the sugar cane stalk can be harvested by the sugar cane harvester in a conventional manner.